Potassium has several key functions in the body, including maintenance of potential difference across cell membranes. Potassium is responsible for regulating DNA and protein and glycogen synthesis. Potassium enters the body when food is ingested. Most potassium loss occurs via the kidneys, and a small amount is lost in sweat and feces. Redistribution within the body also plays a significant role in potassium balance. Potassium is principally an intracellular cation.

Hyperkalemia can be life-threatening because of its depressive effects on the heart and nervous systems. Causes of hyperkalemia include renal failure, urinary tract obstruction, urinary bladder rupture, and hypoadrenocorticism. Hypokalemia can produce profound muscle weakness and predispose to cardiac arrhythmia. Causes of hypokalemia include gastrointestinal disease, chronic renal failure (especially in cats), hyperadrenocorticism, and hyperaldosteronism. Loop diuretics, such as furosemide and thiazide, may also cause hypokalemia. Uncontrolled cases of diabetes mellitus may present with normal, elevated, or decreased potassium levels. Insulin therapy rapidly restores potassium levels to normal.
Successful management of patients with a potassium imbalance requires prompt identification and correction of the imbalance while investigating the underlying cause.

Causes, consequences and control of potassium imbalances in small animals. Skelly B. In Practice 24:596-602, 2002.